Focus character for double-negative dielectric volume with regular polygon structure under electric line source

Focus character for double-negative dielectric volume with regular triangular,square and hexagonal structure under electric line source is analyzed using finite difference time domain method. The computation results show that “focus”does not exist in the double-negative dielectric volume, when the excitation is located on the outside extension line of angular bisector of corner angle in double-negative volume with very small permitivity and permeability. The results are compared with Arslanagic’s analytic results and their validity is proved.